5 green marbles to 8 red marbles, if a bag has 40 red marbles, how many green marbles are there?

Question

Each marble bag sold by Deshaun’s marble company contains 5 green marbles for every 8 red marbles. If a bag has 40 red marbles, how many green marbles does it contain?

Answer 1

Hello, Jules.

We will set up proportions to figure it out:

5 green marbles : 8 red marbles which gives you the ratio 5/8

X green marbles : 40 red marbles which gives you the ratio X/40

Now you have to set those two ratios equal to each other and solve for X, the number of green marbles:

5 X

__ = ____

8 40

Cross-multiply: 8*X = 5*40

8*X = 200

Divide both sides by 8: X = 200/8 = 25

So X = 25

If a bag has 40 red marbles, it contains 25 green marbles.